SEM in-situ Fatigue Observation on Crack Initiation and rnGrowth from Inclusion in P/M Rene95 Superalloy

摘要

A special designed experiment was conducted for observing crrnack initiation and growth in P/M Rene95 superalloy under tension-tensirnon loading by self-made SEM in-situ fatigue loading stag. Several alumrnina inclusion particles exposed at the specimen surface were observed rncarefully. During fatigue test inclusions led to cracks initiation. Thrne cracks can be formed by two mechanisms. Generally, the cracks nuclearnted at the interface between inclusion and matrix. Sometimes, cracks wrnere also formed inside the inclusion. As the increase of cycles, some rncracks at the interface between inclusion and matrix broadened and prornpagated along the direction about 45€?to the loading axis. On the othrner hand, the cracks inside the inclusion propagated in the inclusion arnnd towards matrix.